'Goodbye Dodecatheon; Hello Primula!'

[David Lyttle]

I am about to disregard the prime rule for posting on this forum ie lets not spoil a good barney by introducing facts.

I took the rash step of looking up the papers around which this discussion revolves. The formal transfer of Dodecatheon to Primula was done by Austin R Mast and James L Reveal in a publication called Brittonia in 2007. In an earlier 2004 publication in the American Journal of Botany,  Mast and his collaborators present a genetic analysis that shows that the genus Dodecatheon is most closely related to Primula suffrutescens from Western North America. The point is made that Primula parryi  (another Western North American species) is virtually indistinguishable from Dodecatheon jeffreyi  "when the corollas and inserted anthers are removed".
The conclusion is that Dodecatheon evolved from Primula in Western North America.

The authors then consider how the Dodecatheon flower arose from an ancestral Primula flower. Basically  they propose that it involved modification of the pin/thrum determinant genes with additional changes to produce the characteristic Dodecatheon flower morphology ie changes in relatively few genes affecting flower morphology.  This gives rise the so called " Buzz-pollinated flower " of Dodecatheon so the net result is a change in the pollination system.  In evolutionary terms Dodecatheon flowers evolved to support/respond to different pollinators.

So where does all this leave us; Dodecatheons are specialised North American Primulas that evolved a different pollination system. The same type of pollination system arose independently in Cyclamen.                                                                                                       

Lesley, I hope that now you have mastered the system you would not mistakenly grab the bottle of   PlMaRoEuEuRiCo to have with your pancakes and cream. 

[Joakim B]

Sorry for a maybe stupid question:
Is not the pollination system of such importance that it is used to separate families as well as species? For orchids of Opfrys type there is suggestions that every different pollinator makes the flower different enough to make it a species. Maybe a bit of an over-kill but still the point of a (very?) different would make the difference obvious or?
Hence I would not understand why the authors put them as same family.
Kind regards
Joakim

PS Reading reference articles are considered as cheating in some circles 

[annew]

OOh, it is a good barney! Does that mean cyclamen should be renamed primulas too? 

[Joakim B]

Anne or the argument is that since they did not renamed Cyclamen they should not have renamed Dodecatheon. At least if I understood David correctly.
Please correct me if I got it all wrong.
Kind regards
Joakim

[Giles]

I'm changing my name
  - and emigrating.......

[Carlo]

To what genus?

[Carlo]

I love plant names...and the process. It's fascinating...and unending source of discussion material.

In the end, however, I grow what I'm interested in--and take a fancy to--and the name is a secondary consideration. I have BOTH primula and dodecatheon in the gardens, as I suspect many on this forum do. I try to keep my records reasonably current and accurate as far as names go, but will be keeping dodecatheon for the time being, just as I kept chrysanthemum until the genus was, more or less, put back together...

[Lesley Cox]

Lesley, I hope that now you have mastered the system you would not mistakenly grab the bottle of   PlMaRoEuEuRiCo to have with your pancakes and cream. 

Well you know me David, I'll drink anything - once!

[David Lyttle]

Joakim,

In traditional taxonomy that relies on morphological features for classification flower structure is very important in in determining species genus family etc. The assumption is that structure  of the reproductive parts is less plastic than other characters such as leaf shape and which can vary due to adaptations to the environment ie as in xerophytic leaves. When genetic analysis reveals a relationship that is at odds with that arrived at by more traditional methods (floral morphology)then these contradictions need to be reconciled. The authors of the Dodecatheon paper have in fact done this by re-interpreting the structure of the Dodecatheon flower in terms of its relationship to the more typical Primula flower. Their conclusion is that Dodecatheons are a group of Primulas that have evolved a specialised pollination system and the flower structure you recognize as a Dodecatheon is a consequence of this change.

As modern methods of genetic analysis become powerful and widely employed there will doubtless be further " upsets "  to current views.

Anne,

There is no compelling reason to subsume Cyclamen into Primula: I am assuming the split between the two genera occurred prior to the Primula diversifying to the extent we see today and the two genera are now  genetically more distant. A similar change in floral morphology to that leading to Dodecatheon would have occurred in the most recent common ancestor of Cylamen and Primula leading to Cyclamen.

[Joakim B]

David thanks for the information. It is nice to learn more.

Kind regards
Joakim

[Afloden]

 The last few papers on Cyclamen place it in the Myrsinaceae (in the Primulales) with Lysimachia! It's a good thing I know of no one (private gardener) that writes the family on a label also.   

 Reveal's paper was available on the internet for free most of last year. It may still be.
 
Aaron Floden
Knoxville, TN

edit :
Paper on transfer of Dodecatheon to Primula is available free :
www.botany.wisc.edu/courses/botany_940/11JClub/MastReveal2007.pdf